ABSTRACT

In order to use integrated positron emission tomography/magnetic resonance (PET/MR) systems in a cost-effective way and to make the examination tolerable for patients, total imaging time is the most important parameter of clinical imaging protocols. The general consensus states that an oncological whole-body fluorodeoxyglucose (FDG) PET/MR examination should be completed within 30 minutes, similarly to the whole-body PET/computerized tomography (CT) examination. At the same time, the MR images acquired during the whole-body PET/MR examination should contribute to diagnosis as well as the low-dose CT images acquired in the PET/CT examination. Since the PET part comprises the main diagnostic information in integrated PET/MR studies, specifically established MR protocols are necessary that differ from diagnostic MR studies and which may be completed in a limited time and make a contribution to evaluation of PET findings. The most commonly used protocol in oncological whole-body FDG PET/MR studies is to have axial and/or coronal T1- and T2-weighted MR images simultaneously within the PET acquisition time window. This protocol may also involve acquisition of additional MR sequences which may be necessary according to the clinical diagnostic indication and that will not extend the total imaging duration. Previous clinical studies showed that such an imaging protocol yielded successful results comparable to PET/CT in oncology. In this article, we discuss how the integrated PET/MR system should clinically be used according to the findings in literature and our own experiences.